It's no secret what the Phillies thought Biddle needed to work on most after spending last season at Reading and then getting his first invitation to big-league spring training this year.
"Definitely just commanding his fastball," said Carlos Arroyo, the team's minor-league pitching coordinator. "Last year, he walked 80-something guys. That tells the story. He's a young man and there's no reason to rush him to another level when he has not shown the ability to command the strike zone yet."
Biddle, the Phillies' 2010 first-round pick from Germantown Friends School, walked a league-high 82 batters last season when he went 5-14 with a 3.64 earned run average. He also struck out 154 batters, which ranked third in the Eastern League, but Biddle concedes he fell short of his own expectations last season.
"I guess I was maybe a little bit confused [about returning to Reading], but at the same time, why would I be" promoted?" he said. "I wasn't happy with my year last year, so why would they be? What I expected out of myself was a much more consistent year than what I gave, and I just want to prove to them that I can be that go-to guy that they expect me to be."
Biddle, 22, actually has more than just throwing strikes to work on before he's ready to make the jump to triple-A Lehigh Valley, let alone the big-league club. Fielding and throwing to bases have also been an issue recently. Two starts ago, the lefthander was charged with three errors - one fielding, one throwing and one on a pickoff attempt - during a 9-3 loss to Harrisburg, the Washington Nationals' double-A affiliate.
Another errant pickoff throw Friday night against Harrisburg gave him four errors for the season.
"Yeah, I have been struggling with it a little bit," Biddle said. "I've been working on it a lot with my coaches, but the game at Harrisburg, it was just one inning. Everything happened so quickly. It just kind of got out of my hands and got away from me.
"That was a test of my mental toughness and my mental stability. I was still able to make pitches to home. I actually threw pretty decently, but I kind of let the errors compound [things] and you can't let that happen."
Baseball is filled with stories about players who have encountered mental blocks throwing a baseball, but Biddle said that's not his issue.
"For me, it's just footwork," he said. "The problem is you spend all day throwing 60 feet, 6 inches and now all of a sudden you ask me to throw 20 feet and I try to pitch it over there. I'm going through some of that right now, but it's nothing that I can't fix. That's nothing that is going to stop me from getting to the big leagues."
Biddle started his repeat season at Reading by going 0-2 with a 5.02 ERA in his first three starts. He walked five and hit a batter and allowed 19 hits in 141/3 innings.
He rebounded Friday night in his second straight start against Harrisburg with his best performance of the season, holding the Senators to two hits and striking out 11 over seven innings.
"It was a good step forward for him," Arroyo said. "He was down in the zone. He had a couple misses up, but when you're mostly down in the zone it's a different story. You can get by with a few pitches up."
The test going forward for Biddle will be consistency. Mentally, he feels like he is growing up.
"I think last year I was probably getting a little bit too ahead of myself at some points," he said. "Maybe getting just too frustrated with some of my performances and letting it affect my future ones.
"I didn't have a great outing two starts ago and then I came back and I had a good one [Friday] night. That's because I didn't let the last one affect the next one and I'm not going to let this one affect the next one."
He would, however, be more than happy to repeat what he did Friday for the rest of the season, because that's the ticket that will get him out of Reading and eventually get him back to his hometown of Philadelphia.